Hydraulic feed system of metals and other cutting machines



Jan. 30, 1962 .1. ANDERSON 3,018,629

HYDRAULIC FEED SYSTEM OF METALS AND OTHER CUTTING MACHINES Filed April 8, 1959 r v hump azizzders on/ 3,l8,fi29 Patented Jan. 30, 1962 3,018,629 HYDRAULIC FEED SYSTEM METALS AND OTHER CUTTING MACHENES James Anderson, Glasgow, Scotland, assignor to Vertimax Limited, Glasgow, Scotland Filed Apr. 8, 1959, Ser. No. 804,982 Claims priority, application Great Britain Apr. 18, 1953 (Ilaims. (Cl. 60-97) This invention relates to the hydraulic feed for the cutting tool of a metal and other cutting machine and particularly to an hydraulic feed wherein the movement of the tool is controlled by a pair of hydraulic cylinder and piston assemblies with their axes at an angle to each other, pressure fluid to said assemblies being cont-rolled by a tracer valve operated by a template whereby the tool is moved in a path determined by the formation of the template.

In such hydraulic feed for cutting tools as heretofore constructed each piston partakes of a hunting movement and the present invention has for its object to provide a hydraulic feed wherein the cutting tool will more closely follow the contour of the template than has heretofore been possible.

According to the present invention a hydraulic feed for the cutting tool of a metal and other cutting machine comprises a first slide, a hydraulic piston and cylinder assembly for feeding said slide, a second slide carried by the first slide and to which the cutting tool is or can be secured, a hydraulic cylinder and differential piston for feed ing the second slide, a hydraulic system by which pressure fluid is delivered simultaneously to the piston of the first slide and to the smaller area of the differential piston of the second slide and a tracer valve by which the fluid acting on the larger area of the differential piston can be exhausted, the exhaust cut off and by which pressure fluid can be admitted to act on the larger area of the piston, the construction and arrangement being such that when said fluid is being exhausted the second slide is moved, when the exhaust is cut off pressure builds up on the piston of the first slide which is then fed, and when pressure fluid is admitted to act on the larger area of the differential piston the movement of said piston is reversed.

The invention also consists in a hydraulic feed for a metal and other cutting machine comprising a first cylinder and differential piston assembly, a second cylinder and differential piston assembly which is moved as a unit by the first piston, the cutting tool being connected to the second piston, a hydraulic pressure supply system by which hydraulic fluid at a reduced pressure can be admitted to act continuously on the larger area of the first differential piston and on the smaller area of the second differential piston, and by which fluid at higher pressure can be admitted to act on the smaller area or" the first piston, and a tracer valve which moves in unison with the second piston and which in one position exhausts the fluid on the larger area of the second piston so that the said piston is moved by the pressure on its smaller area, when in a second position it interrupts the said exhaust so that pressure builds up on the larger area of the first piston which moves the second assembly as a unit and when in a third position admits the reduced pressure to act on the larger area of the second piston which is thereby moved against the action of the pressure fluid acting on its smaller area, a combination of such movements being obtained when the tracer valve is in intermediate positions.

The invention further consists in a hydraulic feed as set forth in the preceding paragraph having a pilot valve connected to a reduced pressure supply and also to the line pressure, said valve, when subjected to the reduced pressure, permitting the aforesaid exhaust from the second cylinder and through the pilot valve and when said reduced pressure is cut off supplying line pressure through the tracer valve to the second cylinder to return the piston therein to its initial position, the first piston being simultaneously returned to its initial position by line pressure acting on the smaller area thereof.

The invention further consists in a hydraulic feed system as set forth in the preceding paragraph wherein the tracer valve consists in a valve body having ports con nected to a reduced pressure fluid supply line, and to the second cylinder above and below the differential piston, and a valve element therein is in the form of a spool with bore and having ports therein which, when the spool is removed axially relative to the valve body, places the ports in the valve body in communication with the port connected to one side of the second differential piston and when moved further in the same direction connects that port in the valve body which is connected to the reduced pressure line with the other side of the said cylinder.

The invention further consists in a hydraulic feed system as set forth in the preceding paragraph wherein the valve body carries an adjustable stop extending through and closing the upper end of the bore in the valve element, the foot of the stop masking the ports in the valve element to an adjustable extent so that before the exhaust of the pressure fluid from one side of the second cylinder is completely cut off pressure fluid is commencing to pass to the other end of the cylinder, the overlapping ensuring that the cutting tool does not make a series of fine steps when such is not required by the template.

A preferred embodiment of the invention will now be described with reference to the accompanying drawing wherein A designates a three-Way valve, B designates a first hydraulic cylinder and piston assembly the axis of which is horizontal, C designates a slide which carries a second hydraulic cylinder and piston assembly, this assembly being designated D and having its axis vertical, E designates a tracer valve, F designates a pilot valve and G designates a template.

Line pressure is supplied by a pump H to a metering device I which supplies metered hydraulic fluid at controlled pressure through pipeline 1 to the three-way valve A which valve supplies the metered fluid through pipeline 3. Also connected to said valve is an exhaust pipeline 2. The pump also supplies line pressure to pipeline 17 and to an accumulator J.

The assembly B consists of a cylinder 4 with a piston rod 5 having a piston head 6. To the head of this cylinder is connected the pipeline 3 and also a pipeline 7 which leads to a passage 8 in the body of the pilot valve F. Said valve body 9 is provided with a bore 9a in which is a valve element 10 having a land 11 with a waist 11a which is in communication with a bore 12 in said element and also having a land 13. One end of the bore 9a is closed by a cap 14 and the other end is closed by a cap 14a having an exhaust outlet 15. A helical compression spring 16 interposed between the cap 14a and land 13 biases the valve element to the right.

Line pressure is supplied through the pipeline 17 to the annular space 18 formed between the piston rod 5 and cylinder 4 so as to act on the smaller area of the piston head 6 and line pressure is also supplied through pipeline 19 to a passage 29 in the valve body 9 leading to the annular space 21 between the lands 11 and 13. Also communicating with said space 21 is a passage 21a which is connected by means of a pipeline 22 with passage 23 in the valve body 24 of the tracer valve. This valve body is provided with a bore, a second passage 25 connected to pipeline 25a and a further passage 26 positioned a little higher than the passage 25 and connected by pipeline 25b to pipeline 3.

The valve element of the tracer valve consists of a spool 27 having a bore 28 closed at its lower end. The lower end of the spool is reduced to form an annular chamber 29 in communication with the passage 23 and the reduced end is provided with ports 30 communicating with the bore and said chamber.

The spool is further provided with an annular recess 31 which is of such size in an axial direction that when the valve element is moved axially, as will be hereafter explained, the passage 25 remains uncovered thereby. Further said recess is such that when the valve element is in the position shown it is just on the point of uncover ing the passage 26 on being raised. The annular recess 31 communicates through ports 32 with the bore. Screwed into the valve body is a spindle 33 which seals the upper end of the bore and at its lower end masks the ports 32 to an adjustable extent.

The second hydraulic assembly consists of a cylinder 34 which is carried by the slide C and is provided with a central diaphragm 35 through which passes a piston rod 36 which at its upper end carries a piston head 37. Secured to the piston head to travel therewith is a cylindrical member 38 which passes through the upper end of the cylinder and carries therewith the tracer valve body 24.

Said cylindrical member forms, together with the upper face of the piston head 37 and the cylinder 34, an an nular chamber 39 which is connected by a pipeline 40 to pipeline 25b.

The diaphragm and piston head form a second annular chamber 41 in the cylinder, this chamber being of greater cross sectional area than that of chamber 39 and at its lower end is connected by pipeline 25a with the passage 25 in the tracer valve.

The piston rod 36 at its lower end is provided with a cylindrical member 43, which constitutes the second slide and is guided within the lower part of the cylinder. This second slide carries a cutting tool 44.

When the three-way valve is operated so that metered pressure fluid at lower than line pressure passes through the pipeline 3 the pressure is transmitted through the fluid in the outer end of cylinder 4 and through the pipeline 7 to act on the right hand end of spool 10 which is thereby moved to the left against the action of its spring 16 thereby placing its waist 11a in communication with the passage 21a. The fluid in chamber 41 is thereby opened to exhaust through pipeline 25a, through the bore in tracer valve element, through pipeline 22 and through the bore 12 in pilot valve element to exhaust 15. Simultaneously similar pressure fluid is supplied through pipeline 25b and 40 to the top of piston head 37. There is now no resistance to the downward movement of this piston head so that it, together with the cylindrical member 43, the tool 44 and the tracer valve body 24, likewise moves downwards, During such movement pressure cannot be built up in the end of the first hydraulic cylinder and ram assembly so that no, or very little, horizontal movement is imparted to the piston and slide C. When the tracer valve is lowered to such extent that its valve element cont-acts the template G its valve element is raised relative to the valve body and the ports 32 completely masked by the spindle 33. The fluid in chamber 41 is thereby trapped and pressure is built up in the end of cylinder 4 so that the slide together with the second cylinder and piston assembly and the cutting tool is moved horizontally. So long as the tracer valve contacts with a horizontal portion of the template such horizontal movement will continue. Should the template dip the tracer valve element will move downwards and again open the chamber 41 to exhaust. The pressure of the fluid in chamber 39 again moves the tool downwards but pressure in the end of the cylinder 4 is reduced so that the horizontal movement of the tool is arrested or substantially arrested. If the template is such that it does not dip but raises the tracer valve element the annular recess 31 registers with the passage 26 so that pressure fluid is then supplied through said passage, the annular recess 31 and pipeline 25a to chamber 41 As the area of the underface of the piston 37 on which the pressure fluid acts is greater than that of the upper face of the piston the piston together with the tool is thereby raised.

The resistance offered to such movement is substantially less than that olfered to the continued horizontal movement of the piston 5 by reason of the main line pressure in the chamber 18 and the aforesaid horizontal movement is slowed down or arrested.

It will be understood that the template may be such that the tracer valve is moved to intermediate positions so that both pistons are simultaneously operated and the movement of the tool is the resultant of such combined movements. Thus the movement of the tool corresponds to the formation of the template.

It is very desirable that there should be a slight overlap in shutting ports 32 and uncovering the end of passage 26. This requires fine adjustment which is effected by turning the spindle 33 to raise and lower it as is found necessary.

At the end of the cutting operation the three-way valve is opened to exhaust so that the pilot valve resumes its initial position. Line pressure in chamber 18 moves the piston rod 5 and slide C to the right and line pressure passes through pipeline 22, through the tracer valve to chamber 41 so that the piston rod 36 carrying the tool is also raised to its initial position.

I claim:

1. In a hydraulic feed for the tool of a metal and other machine, including a template, a first slide, a hydraulic piston and cylinder assembly for feeding and retracting said slide with respect to a work-piece on which the tool is operating, a second slide carried by the first slide and to which the tool can be secured, a hydraulic cylinder and differential piston for feeding the second slide at right angles to the movement of the first slide, the improved hydraulic system comprising tubes and at least one valve by which hydraulic pressure fluid is delivered simultaneously to the piston of the first slide and to a smaller area of the differential piston of the second slide, said valve being a tracer valve influenced by said template and by which valve the fluid acting on a larger area of the diflerential piston can be exhausted, held, or by which pressure fluid can be admitted to act on the larger area of the piston to move said second slide according to the shape of said template, the construction and arrangement being such that when said fluid is being exhausted the second slide is moved in one direction relative to the work-piece, when the exhaust is cut off pressure builds up on the piston of the first slide which is then fed at right angles to the movement of the second slide, and when pressure fluid is admitted to act on the larger area of the differential piston the movement of said piston is reversed.

2. A hydraulic feed for the cutting tool of a metal and other cutting machine comprising a first slide, a first hydraulic cylinder and differential piston assembly for feeding said slide in one direction relative to a workpiece, a second slide carried by the first slide and to which a tool can be secured, a second hydraulic cylinder and differential piston assembly for feeding the second slide at right angles to the movement of the first slide, pipelines by which metered hydraulic fluid is delivered simultaneously and continuously to said two cylinders to act on a larger area of the piston of the first assembly and on a smaller area of the piston of the second assembly, a pipeline by which line pressure is simultaneously and continuously delivered to the first cylinder to act on the smaller area of the piston therein, a tracer valve comprising a valve body supported to move in unison with the second slide, said body having ports therein, a pipeline by which the metered hydraulic fluid is delivered to one of said ports, a pipeline connecting the other port to the second cylinder and through which metered hydraulic fluid can be admitted to act on a larger area of the second piston and through which said fluid can be exhausted, and a valve element reciprocable within said body under the action of a template to cover and uncover said ports and which, when in one position, permits fluid acting on the smaller area of the second piston to exhaust whereon the said piston and the second slide are moved by the metered fluid acting on the smaller area of the second piston and pressure on the larger area of the first piston prevented from building up, when in a second position the valve traps the fluid acting on the larger area of the second piston so that the movement of the second slide is arrested and pressure builds up on the larger area of the first piston which then moves the first slide together with the second slide, and when in a third position admits metered fluid to act on the larger area of the second piston which is then moved together with its slide in the reverse direction, pressure being again prevented from building up on the larger area of the first piston.

3. A hydraulic feed system as claimed in claim 2 wherein the valve element is in the form of a spool within a bore in the valve body and having an axial bore and ports communicating therewith, the spool, when in the first mentioned position, permitting the fluid acting on the larger area of the piston of the second assembly to exhaust through said ports and axial bore.

4. A hydraulic feed as claimed in claim 3 wherein the valve body carries an adjustable stop extending through and closing the upper end of the bore in the valve element, the foot of the stop masking the ports in the valve element to an adjustable extent so that before the exhaust of the pressure fluid from one side of the second cylinder is completely cut oil. pressure fluid is commencing topass to said side of said cylinder, the overlapping ensuring that the tool does not make a series of fine steps when such is not required by the template.

5. A hydraulic feed as claimed in claim 2, having a further valve comprising a valve body and spool valve reciprocable therein, said spool valve having two lands forming an annular chamber therebetween, one of which lands having a waist communicating with an axial bore in the spool, and which valve body has a first port to which metered fluid is led to act on one end of the spool, a second port to which line pressure is led and a third port connected by a pipeline to the body of the tracer valve and through the tracer valve to the second cylinder, said annular chamber normally bridging the second and third ports so that fluid at line pressure is supplied to act on the larger area of the second piston to return it and the second slide to its initial position while the admission of metered fluid to the valve 'body moves the spool to place the waist in the position where it registers with the port connected to the tracer valve so that the fluid acting on the larger area of the second piston can be exhausted through the tracer valve and through said waist and through said axial bore.

Howe Dec. 31, 1935 Turchan et al. Dec. 25, 1945 

